This invention relates to business forms assemblies and, more specifically, to return-mailer type forms which include return envelopes and at least one window formed in a sheet adjacent the return envelope portion of the mailer.
It is known in the prior art to produce such forms with a so-called "flip-window" construction wherein the window is cut along three edges of a rectangle and folded back about a fourth edge. Accordingly, the resulting flap or panel may be folded back and forth between open and closed positions. This construction has proved advantageous because it permits the exterior side of the flap to be printed along with the interior side of the sheet in which the window is formed in a single printing step.
More specifically, it is usually the case that the interior surface of the top sheet is printed with billing or other account information or the like, while the exterior surface of the flap is printed with, for example, a name and address which faces outwardly when the flap or panel is in a window closing position. To effect simultaneous printing in a single step, the panel is simply folded back onto the interior of the sheet so that the exterior flap surface and interior sheet surface face the printer. This type of return-mailer construction can be found in U.S. Pat. No. 4,598,860.
As will be appreciated, the above described construction requires multiple window opening and closing steps during manufacture of the form, which steps are carried out manually or by machine. In either case, the process is relatively slow and causes many failures due to tearing of the window closing panel. As a result, even more stringent and time consuming inspection procedures are required to assure a quality product.
In the present invention, the above described prior art difficulties are eliminated by a simple redesign of the window closing structure of the form assembly. Specifically, in accordance with the present invention, the window is cut on all four sides and the cut-out panel is discarded. Thereafter, a paper patch or cover, with dimensions slightly larger than the window dimensions, is temporarily attached, by a releasable pressure sensitive adhesive for example, to the outer surface of the next adjacent sheet or web, so that when the sheets are superposed, the patch or cover completely overlies the window and a surrounding marginal area of the lower surface of the top sheet.
In addition, the marginal area surrounding the window has a heat activated adhesive applied thereto, in facing relationship to the patch or cover. When the respective sheets and patch are plied together during manufacture, one side of the patch or cover engages, but does not adhere to, the adhesive surrounding the window, while the other side of the patch is itself provided with pressure sensitive adhesive which temporarily, and releasably, secures the patch to the adjacent sheet.
During certain of the various manufacturing stages, typically involving a continuous web with individual form assemblies defined by transverse lines of perforations, it may be desirable that the top sheet be free of any window closing structure, and thus, in accordance with this invention, the patch will remain temporarily adhered to the next adjacent sheet permitting the top sheet to be manipulated as needed or desired with a completely open window structure. This arrangement also permits printing of the patch simultaneously with the adjacent sheet to which it is temporarily attached.
At a further manufacturing stage, where the form structure is substantially completed, heat is applied to activate the various adhesive lines included in the assembly. At this time, the adhesive applied about the periphery of the window is also activated to bond the patch to the underside of the top sheet, in overlying relationship with the window. At this stage, the patch is adhesively secured to both the top sheet as well as the next adjacent sheet. However, this seemingly undesirable situation is accommodated by the fact that the heat activated adhesive is considerably stronger than the pressure sensitive adhesive. Thus, upon separation of the top or cover sheet from the next adjacent sheet upon opening, the releasable, pressure sensitive adhesive will yield to the greater strength of the heat activated adhesive, and the patch or cover will therefore remain securely attached to the lower surface of the top sheet, covering and closing the window.
It will therefore be appreciated that this invention provides a higher quality product at increased manufacturing speed, resulting in greater forms acceptance rate and, therefore, reduced inspection requirements.
In a related aspect, this invention provides an improved method of manufacturing a business form assembly of the type which includes first and second superposed sheets, and wherein the first sheet is provided with a window, the improved method broadly comprising:
(a) providing a third sheet having a dimension greater than the window but lesser than the first and second sheets;
(b) temporarily and releasably adhering the third sheet to the second sheet during a first stage of manufacture; and
(d) permanently securing the third sheet to the first sheet during a second stage of manufacture.
Further objects and advantages of the invention will become apparent form the detailed description which follows.